Lab Reports
Everything You Didn’t Want to Know!
Components of a Lab Report
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Title
Purpose
Procedure
Safety
Data
Calculations
Conclusion
How to Write a Lab Report
Title:
•Placed at top center of page one
Density of Solids
•Descriptive and appropriate
Purpose:
•One sentence telling why the lab
was performed
Procedure:
•A paragraph summarizing how the lab was
performed.
•Include key concept(s), formula, and/or
Purpose: TPOTLIT investigate the density of
various solids.
Procedure: The relationship between the mass
of an object and its volume is called density.
The mass and volume of various cubed shaped
substances were determined. The density was
calculated by dividing the mass of the cube by
its volume.
chemical equation
Safety:
•Specify safety rules by contract #
Safety: #1,4,5,7 & 8
Data
Includes both qualitative and
quantitative observations
Quantitative data should be
arranged in a data table
format
Always use units of
measurements
Always use Significant
Figures
Data:
Cylinder
Mass (g) Volume (ml) Density (g/ml)
aluminum
copper
brass
lead
iron
5.40
18.00
15.60
22.80
15.80
1.8
2.0
2.0
2.0
2.0
3.0
9.0
7.8
11.4
7.9
Calculations
* Show a sample of
how the calculation was
performed.
* Usually use first data
set
* Write Formula
* Sub in #s with units
* Answer with units rounded
off to the correct # of sig
figs
Calculations:
D = M
V
D = 5.40 g
2.0 ml
D = 2.7 g/ml
Conclusion
It is the most important part of the lab
report.
It is where you tell me what you learned
from the lab.
It always relates back to the purpose of
the lab.
It should include a discussion of sources
of error.
It is written in the third person.
Conclusion: Different materials seem to have different
densities. The five cubes have the same volume but
their masses are different and consequently they have
different densities. Aluminum, copper and lead have
densities that are very different from each other. Of
these three aluminum has the smallest density and lead
has the largest density. Brass and iron have similar
densities.
The density of the copper, brass, lead and iron cubes
are exactly the same as the values reported in the CRC
handbook of chemistry and physics. The density of
aluminum should have been 2.7 g/ml. A source of
error in this experiment is the measurement of the
volume of the cubes using the water displacement
method. When the cubes were dropped into the
graduated cylinder water tended to splash out. This
made the volume of the cube smaller than it really was
and the density of the cube larger than the actual
value. This would account for the measured density
of aluminum being 3.0 g/ml.
It could suggest further investigations.
Another experiment might be to measure the
density of aluminum cubes that have different
volumes. If the densities of these cubes were the
same, density would be a characteristic property. A
characteristic property allows one to distinguish
substances regardless of the size of sample tested.
Conclusion
Conclusion: Different materials seem to have different densities. The five cubes
have the same volume but their masses are different and consequently they have
different densities. Aluminum, copper and lead have densities that are very different
from each other. Of these three aluminum has the smallest density and lead has the
largest density. Brass and iron have similar densities.
The density of the copper, brass, lead and iron cubes are exactly the same as
the values reported in the CRC handbook of Chemistry and Physics. The density of
aluminum should have been 2.7 g/ml. A source of error in this experiment is the
measurement of the volume of the cubes using the water displacement method.
When the cubes were dropped into the graduated cylinder water tended to splash out.
This made the volume of the cube smaller than it really was and the density of the
cube larger than the actual value. This would account for the measured density of
aluminum being 3.0 g/ml.
Another experiment might be to measure the density of aluminum cubes that
have different volumes. If the densities of these cubes were the same, density would
be a characteristic property. A characteristic property allows one to distinguish
substances regardless of the size of the sample tested.
Sample Lab Report - Qualitative Data
Raw Eggs and Chemicals
Purpose: TPOTLIT investigate the effects of chemicals on raw eggs.
Procedure: Sulfuric acid was added to a raw egg. In order to neutralize the acid, sodium hydroxide
was then added. As a last resort, water was added to the raw egg.
Safety: #23, 26, 31
Data:
Observations
Raw Egg
Yellow yolk in center, 1” diameter Egg white clear, surrounding
the yolk
Raw Egg with Acid
Yolk congealed Egg white congealed and became opaque
Raw Egg with Base
Egg became gel like
Raw Egg with Water
Spread out the mixture
Conclusion: When the acid was added to the egg a chemical reaction occurred forming a white
substance that was opaque. Although bases neutralize acids when the base was added the egg did
not return to its normal state. This indicates that the acid was no longer present when the base was
added because the acid had reacted with materials in the egg. Instead, the base reacted with the
remaining material and formed a gel. This indicates that another chemical reaction occurred. The
water was not able to return the egg to its “normal” state. The only effect of the water is to dilute the
remaining chemicals.
This activity demonstrated the meaning of the words “corrosive” and “caustic”. In a chemical
sense these words mean “to destroy”. Since human eyes are made of protein materials just as the
egg, this activity demonstrated the importance of always wearing safety glasses when performing
F A Q’ S
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Yes, each person must record all data while performing the lab.
Yes, all parts of the lab reports must be typed and each section clearly
labeled.
Yes, each person must submit his/her own lab report.
Yes, you may help each other with the calculations but each person
must work individually on the conclusion.
NO, “warm and fuzzy” and personal comments are not included in the
lab report. Especially conclusions. ie “I really liked this lab. It was
easy to do. I learned a lot about density.”
Yes, the lab report must be in the proper order.
Reports are due on the following block lab day.
Only one late lab report will be accepted a marking period.
Yes, there is a 10 point penalty for each day that the report is late.
EXTRA CREDIT: 10 point bonus if turned in before due date!
Lab Report MUST be complete.
Rubric for Lab Report
Component
Description
Points
Title
Clear and concise
1 point
Purpose
One sentence why the lab was
performed
2 points
Procedure
One paragraph summarizing how
the lab was performed
2 points
Safety
Rules cited by #
5 points
Data
Qualitative and quantitative
observations
5 – 10 points
Calculations
Sample calculation using problem
solving technique
5 – 10 points
Conclusion
Analysis of what was learned from
the lab including error analysis
20 – 30
points
Rubric for Lab Technique
Category
Points
Participation in lab and
Pre-Lab – Data – Post
Lab Sheet
20 points
Accuracy of data
10 points
Adherence to safety rules 10 points
Cleaning of equipment
and lab station
10 points
Laboratory Make-Up Policy
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All labs are made up after school at 2:15PM
on the following Thursday or Friday for Wednesday blocks
and Friday or Monday for Thursday blocks.
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If you are on a field trip on lab day, plan on making up the
lab that day at 2:15 PM.
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If you miss a lab, see me to schedule make-up.
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Once corrected labs are passed back to the class, late labs
for that experiment can not be accepted.
Lastly
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If you have questions
or need help…
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Please ASK!